Method of dispersing keratin proteins and the composition resulting therefrom



Patented Aug. 24, 1948 METHOD OF DISPERSING KERATIN PRO- TEINS AND THE COMPOSITION RESULT- ING THEREFROM Chase B. Jones and Dale K. Mecham, Berkeley,

Calif., assignors to United States of America as represented by the Secretary of Agriculture No Drawing.

Application November 7, 1944, Serial No. 562,326

6 Claims. (Cl. 106-155) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by-or for According to Our invention, keratin materials are dispersed under mild conditions, that is, in neutral or practically neutral reaction, and at relatively low temperatures. These conditions the Government of the United States of America 5 produce less degradation of the original keratin for governmental purposes without the payment than occurred in the prior art and the dispersed to us of any royalty thereon. keratin may be recovered in a form substantially This invention relates to a method of disperssimilar to that of the original keratin in regard to ing keratin proteins obtained from a keratin maits composition, isoelectric point, solubility, and terial such as feathers, hoofs, horns, wool, and so other properties. forth, and has among its objects the use of such The method involved in this invention is based keratins, either in the dispersed or recovered partly on the reduction of the disulfide bonds forms, in the preparation of artificial fibers, films, within the keratin molecule by treating it with a plastics and the like. sulfur-containing, reductive disulfide-splitting Keratins, like the more soluble proteins, can be agent such as monoethylene thioglycol (thioreadily dispersed by hydrolysis in strong acids or glycol), thioglycolic acid (present as the thioalkalis, but the keratin thus dispersed cannot be glycolate in neutral solution), and sodium bisulrecovered except as simple degradation products, fite. I such as amino acids, or complex degradation The presence of alkali is obviated by the use of products, such as peptides, peptones, and proany ofanumber of protein-denaturing or proteinteoses, the properties of which differ radically dispersing agents, such as urea, gu-anidine hydrofrom those of the original keratin. chloride, ammonium thiocyanate, formamide, Keratins can alsobe dispersed in alkaline soluacetamide, thiourea, sodium salicylate, urethane, tions of metallic sulfides and such sulfides are phenol, lithium iodide, and surface-active agents, commonly used in cosmetic depilatories and in such as synthetic detergents composed of sodium the removal of hair from hides in the tanning inalkyl aryl sulfonates, sodium alkyl sulfates, and dustry. so forth, and dispersion of the keratin is thus ef- Keratins have also been dispersed at neutral iected at neutral, or practically neutral reaction. reactions but in these cases heat and high tem- Therefore, under the above conditions of emperatures were employed to the point of charring, ploying disulfide-splitting and protein-dispersing which produced drastic degradation of the pro or protein-denaturing agents to effect the disperteins. sion in neutral or practically neutral reaction and Also, keratins maybe dispersed in strong alkaat relatively low temperatures, the keratin moleline solutions by treatment with reducing agents, cule undergoes minimal degradation, the Only and the recovered proteinis more similar to the 5 chemical attack on the covalent linkages of the original protein in regard to solubility, molecular keratin being the cleavage of the disulfide bonds size, and so forth, than are the peptides, proof the cystine moiety. teoses, etc., referred to previously. However, the The following examples are illustrative of our presence of the strong alkali is undesirable beinvention: cause it presents an opportunity for the hydro- 40 Exam ne I lysis f t k destructive of the cystine 1.4 parts of monothioethylene glycol and 27.2 constituent of the ke (keravms being umque parts of guanidine hydrochloride are dissolved in among Proteins i that ey Contain exceptionab water. Sodium hydroxide solution and water are ly large amounts of cystine) and destruction of then added as required to obtain 35 parts of soluthe hydroxy amino'acid residues of the keratin.

tion at about pH 6.9. 2.5 parts of cattle hoof filings are treated with this neutralized solution in a water bath at about 40 C. about for 18 hours. The mixture is stirred at convenient intervals. During this period about 74% of the hoof keratin is dispersed in the solution. After removal of the undispersed hoof by filtration, the dispersed keratin may be precipitated either by dilution with several volumes of water, by salting out with MgSO4, (NH4)2SO4, etc., by acidification, or by dialysis. If desired, the guanidine may be removed from the dispersion by dialysis and may be recovered from the dialysate by precipitation as the nitrate or by other suitable means.

EXAMPLE II 1.1 parts of NaHSO; and 21 parts of urea are dissolved in water. Sodium hydroxide solution and water are added as required to obtain 35 parts of solution at about pH 7.1. 2.5 parts of wool are treated with this solution in a water bath at about 40 C. about for 18 hours, during which period the mixture is stirred at frequent intervals. 52% of the original weight of the wool is dispersed by this treatment. The dispersed wool may be precipitated and recovered from the solution either by dialysis, by salting out with MgSO4, (NH4)2SO4, etc., or by careful addition of a suitable amount of acid or alkali.

EXAMPLE III 40 parts of a synthetic detergent composed of sodium alkyl aryl sulfonates, and 4 parts of NaI-ISOs are dissolved in water. Sodium hydroxide solution and water are added as required to obtain 400 parts of solution at about pH 6.6. This solution is heated to boiling and 64 parts of chicken feathers are added. The solution is kept boiling gently for about 30 minutes with frequent stirring. During this period considerable dispersion of the feathers occurs and the undispersed portion becomes very soft and loses its original shape. 200 parts of boiling water are now added and the solution is boiled and.

stirred for about another 30 minutes. The undispersed residue is removed by suitable filtration and is washed several times in hot water. The washings and filtrate may be combined and evaporated to dryness to obtain 70 parts of a water-soluble product that has been found useful for the preparation of artificial fibers. This material contains 8.5% to 8.6% nitrogen on a dry basis.

' EXAMPLE IV 50 parts of a synthetic detergent, composed of sodium a-lkyl'sulfates, and parts of NaHSOa are dissolved in 940 parts of water. A saturated solution of sodium hydroxide is added until the pH of the solution is about 6.0. This solution is heated to boiling and 80 parts of chicken features are added. The solution is gently boiled for about one hour with frequent stirring. The undispersed residue is removed by suitable filtration and is washed several times in hot water. The combined washings and fllterrate are evaporated to dryness. 75 parts of dry product are obtained having a nitrogen content of 8.5% to 8.6%. This material has been found useful for the preparation of artificial fibers.

EXAMPLE V 1.6 parts of thioglycolic acid and 21 parts of urea are dissolved in water. Sodium hydroxide solution and water are added as required to obtain 35 parts of solution at about pH 7.0 (:0.2). 2.5 parts of duck feathers are added, and the mixture is heated at about 40 C. about for 18 hours. About 78% of the feather keratin is dispersed by this treatment.

EXAMPLE VI 1.4 parts of monothioethylene glycol and 24 parts of ammonium thiocyanate are dissolved in water. Sodium hydroxide solution and water are added'as required to obtain 35 parts of solution having a pH of about 6.9. 2.5 parts of chicken feathers are treated with this solution for about 18 hours at about 40 C. During this period about 82% of the feather keratin is dispersed.

EXAMPLE VII 1.4 parts of monothioethylene glycol and 20.7 parts of acetamide are dissolved in water. Sodium hydroxide solution and water are added to give 35 parts of solution having a pH of about 7.2. 2.5 parts of chicken feathers are treated with this solution at about 40 C. about for 18 hours. During this period about 59% of the feather keratin is dispersed.

EXAMPLE VIII 1.4 parts of monothioethylene glycol and 27.2 parts of guanidine hydrochloride are dissolved in water. Sodium hydroxide solution and water are added as required to obtain 35 parts of solution having a pH of about 7.0. 2.5 parts of hog hair are added and the mixture is heated at about 40 0. about for 18 hours. About 56% of the hair is dispersed during this period.

In addition to the foregoing examples, many other experiments were performed, the results of which are shown in the following tables:

TABLE I Dispersibz'lities of keratins in difi'erent dispersing agent upon reduction by 0.5 M thzoglycol [2.5 g. of keratin was treated for 18 hours at about 40 C. with 35 ml. of solution at pH 7.]

Guani- Form- Acet- S nthetic Keratin amide amide D tergent 1 (m M) 10.0 M) (10.0 M) 10% Chicken feather Per cegi Per erg; Per ceg Per cent Per 00% Per cent I Duck'featheLU III I as so 41 36 6 2 Tortoise scutes 64 52 101 8 Snake skin... 55 44 26 30 Cattle ho 74 56 7 e s 58: 64 co] 61 36 4 6 4 44, 60 Cattle born... 36 27 3 5 4 14, 12 Hog hail 56 26 2 2 2 4 3 Human hair 50 ll 0 0 2 2: l Ovokeratin 8 6 4 3 l5 2, 4

1 Composed of sodium alkyl sulfates First values calculated from dry w nitrogen analyses.

eights of residues after acetone extraction; second values calculated from Dispersibilities of keratins in M urea upon reduction by diflerent disulflde-splitting agents [2.5 g. oi keratin was treated for 18 hours at about 40 C. with 35 ml.

for dispersion shown in the foregoing examples and tables may be made. As a rule, the higher the concentration of protein-dispersing or protein-denaturing agent, the greater is the percentage of keratin dispersed, the solubility of the dispersing or denaturing agent being a limiting factor. A greater degree of dispersion may also be obtained in some cases by increasing the concentration of the disulfide-splitting agent, as for example, for monoethylene thioglycol and thioglycolic acid. An increase in the concentration of NaHSOa, however, often results in a decrease in the extent oi. dispersion of the keratin, presumably due to a salting-out eii'ect.

Also, it is not necessary in every case that the solution be near the point of neutrality (pH 7.0).

For example, the dispersibility of human hair in a solution of thioglycol and sodium salicylate is increased as the pH of the solution is increased about from 6.9 to 11.4. The use of neutral solutions merely minimizes the possibility of hydrolytic degradation of the protein which may be detrimental insome cases. If the pH is increased above about pH 10, dispersion occurs it only a disulfide-splitting agent is present; however, the presence of a protein-dispersing or protein-denaturing agent, as used in our inven- 6 1. The process comprising dispersing feathers in an essentially neutral aqueous solution containing monoethylene thioglycol and guanidine hydrochloride at a temperature of about 40 C.

2. The process comprising heating a keratin material in an essentially neutral aqueous solution containing monoethylene thioglycol and guanidine hydrochloride at a temperature up to about C. to disperse said keratin material in said solution.

3. The process comprising heating a keratin material in an essentially neutral aqueous solution containing a sulfur-containing, reductive disuliide-splitting agent and guanidine hydrochloride at a temperature up to about 100 C. to disperse said keratin material in said solution.

4. A composition of matter consisting essentially of a dispersion of feathers in an essentially neutral aqueous solution containing monoethylene thioglycol and guanidine hydrochloride.

5. A composition of matter consisting essentially of a dispersion of a keratin material in an essentially neutral aqueous solution containing monoethylene thioglycol and guanidine hydrochloride.

6. A composition of matter, consisting essentially of a dispersion of a keratin material in an essentially neutral aqueous solution containing a sulfur-containing, reductive disulflde-splitting agent and guanidine hydrochloride.

CHASE B. JONES. DALE K. MECHAM.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,351,718 Speakman June 20, 1944 2,131,145 Schlack Sept. 27, 1938 FOREIGN PATENTS Number Country Date 545,421 Great Britain May 26, 1942 463,043 Great Britain Mar. 16, 1937 443,359 Great Britain Feb. 20, 1936 OTHER REFERENCES J. Biological Chemistry, vol. 106, 1934, pages 605-614.

J. Experimental Medicine, 1939, pages 191-197.

J. American Leather Chemists Assoc, Vol.30, 1935, pages 561-567.

Archives of Biochemistry, vol. 3, No. 2, Dec. 1943, pages 193-201.

r'ature, March 14, 1931, pages 403-404.

Textile Manufacture. April 1940, page 160. 

